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The CBR test is a penetration test in which a standard piston, with a diameter of 50 mm (1.969 in), is used to penetrate the soil at a standard rate of 1.25 mm/minute. Although the force increases with the depth of penetration, in most cases, it does not increase as quickly as it does for the standard crushed rock, so the ratio decreases.
The CBR test gave engineers instantaneous results allowing the amount of aggregate used in runway construction to be calculated to the minimum requirements, thus ensuring rapid construction. The rapid advancement of US airpower was one of the factors that lead to the surrender of the Japanese.
It is a pointed cone attached to a spring-loaded handle by extension spindles. The device is pushed into the ground and a scale reads off the estimated CBR value. It is a quick and simple means of estimating the CBR of the top 0.5 metres of subgrade but is less accurate than the more involved standard CBR test.
The test method consists of pushing an instrumented cone, with the tip facing down, into the ground at a controlled rate (controlled between 1.5 -2.5 cm/s accepted). The resolution of the CPT in delineating stratigraphic layers is related to the size of the cone tip, with typical cone tips having a cross-sectional area of either 10 or 15 cm 2 ...
A proof test is a form of stress test to demonstrate the fitness of a load-bearing or impact-experiencing structure. An individual proof test may apply only to the unit tested, or to its design in general for mass-produced items. Such a structure is often subjected to loads above those expected in actual use, demonstrating safety and design margin.
While CUP and LUP numbers were intended to be comparable to the crushing power of a given pressure, the numbers are not equivalent. Since a longer duration, lower pressure pulse can crush the cylinder as much as a shorter duration, higher pressure pulse, CUP and LUP pressures frequently register lower than actual peak pressures (as measured by a transducer) by up to 20 %.
Crusher buckets can differ in size and weight (1,500–5,620 kilograms (3,310–12,390 lb)) and volume (0.5–1.05 cubic metres (18–37 cu ft)). The distance between the crushing jaws can range from 970 to 1,650 millimetres (38 to 65 in). [1] Most patents on bucket crushers were filed in the mid 1990s, expiring around the year 2020.
The test is suitable for clay soils classified as soft to firm. By remoulding the sample and retesting an indication of the sensitivity of the clay can also be found. [1] The test has also been used to measure the shear strength of mortar mixes, where it has been shown to correlate with the slump value. [2]